1. Field of the Invention
This invention relates to a rugged device for measuring tension in a traveling threadline wherein the device is immune to corrosive environments and the measurement is independent of the location of the application of forces on the sensing element of the device.
2. Description of the Prior Art
U.S. Pat. No. 4,821,583, issued Apr. 18, 1989 on the application of B. D. Richards, discloses a tensionmeter for moving threadlines wherein the theadline can be located within a small but flat, ungrooved, area. The Richards device utilizes twin beams of varying thickness positioned inside of two outer shells. Strain gages are attached directly to the beams at locations of minimum thickness. Although the beams are enveloped in two shells, the strain gages are not sealed from the effects of a hostile or corrosive atmosphere.
U.S. Pat. No. 3,280,623 issued Oct. 25, 1966 on the application of E. J. Saxl discloses a load cell for measurement of low forces wherein the cell is a twisted bar with strain gages mounted thereon without provision for a cartridge to contain the strain gages.
U.S. Pat. No. 3,554,025 issued Jan. 12, 1971 on the application of J. Anderson and R.P. Haggstrom discloses a force measuring device of the bending beam type wherein the strain gages are mounted on the main beam.
U.S. Pat. No. 3,602,866 issued Aug. 31, 1971 on the application of E. J. Saxl, discloses a bending beam type of force measuring device wherein strain is concentrated at a weakened point in the beam.
U.S. Pat. No. 4,295,360 issued Oct. 20, 1981 on the application of F. S. Fountain discloses a tension measuring apparatus wherein strain gages are applied to a beam which is primarily responsible for accepting the tension forces to be measured.
U.S. Pat. No. 4,326,424 issued Apr. 27, 1982 on the application of R. G. Koenig discloses a twin beam device wherein the strain gages are merely attached to the primary load-bearing beams.
U.S. Pat. No. Re 31,312 reissued July 19, 1983 on the application of G. R. Eddens discloses a dual beam bridge construction with strain gages mounted to the beams.
Swiss Patent No. 353,555, published May 31, 1961 in the names of M. Green and R. Laimins, discloses a force measuring device of the twin beam type wherein the force to be measured is to be applied through a hole in one beam and onto an inner projection located between the twin beams.